Control of interfacial properties of Pr-oxide/Ge gate stack structure by introduction of nitrogen

We have demonstrated the control of interfacial properties of Pr-oxide/Ge gate stack structure by the introduction of nitrogen. From C–V characteristics of Al/Pr-oxide/Ge3N4/Ge MOS capacitors, the interface state density decreases without the change of the accumulation capacitance after annealing. The TEM and TED measurements reveal that the crystallization of Pr-oxide is enhanced with annealing and the columnar structure of cubic-Pr2O3 is formed after annealing. From the depth profiles measured using XPS with Ar sputtering for the Pr-oxide/Ge3N4/Ge stack structure, the increase in the Ge component is not observed in a Pr-oxide film and near the interface between a Pr-oxide film and a Ge substrate. In addition, the N component segregates near the interface region, amorphous Pr-oxynitride (PrON) is formed at the interface. As a result, Pr-oxide/PrON/Ge stacked structure without the Ge-oxynitride interlayer is formed.

Research highlights
► Controlling interfacial properties of Pr-oxide/Ge structures by the introduction of nitrogen.
► Nitrogen component segregates at the Pr-oxide/Ge interface.
► Formation of Pr-oxide/PrON/Ge structures without Ge-oxide or Ge-oxynitride interlayer.
► Interface state density as low as 4 × 1011 eV−1 cm−2.